Individuals and organizations may be subjected to the receipt of large amounts of unwanted communication. Examples of unwanted communication include email messages commonly referred to as spam, and telemarketer phone calls and fax calls, etc. Unwanted communication may impose a variety of costs on individuals and organizations. Examples of the costs of unwanted communication include loss of time, productivity, consumption of communication resources, user frustration, etc.
Prior techniques for defending against unwanted communications usually involve message blocking. For example, email programs may include spam filters that deflect, flag, delete, etc., spam email messages. Similarly, telephone systems may be provided with caller ID mechanisms for blocking unwanted phone and fax calls. Likewise, internet service providers may attempt to block transmission channels from known senders of spam email.
Unfortunately, message blocking may fail to stop or even deter the large-scale transmission of unwanted communications. For example, the senders of spam email continue to develop schemes for defeating spam filters and for overcoming attempts to block their transmission channels. In addition, the senders of spam email may be located in jurisdictions that are outside the reach of any legal constraints on spam.